The urban forest is a crucial component our city landscapes, providing communities with countless benefits we refer to as ecosystem services. Trees improve urban air quality, decrease city temperatures, provide spaces for recreation and promote mental wellbeing. To properly quantify the benefits the urban forest provides, we require a strong baseline understanding of forest structure, diversity, and composition. To date, fine-scale work considering urban forest diversity has been commonly limited to trees on public land, considering only one or two green space types. However, the governance of green spaces in cities means tree species composition is often being influenced by management decisions at various levels, including by institutions, municipalities, and individual landowners responsible for their care. Using a mixed-method approach combining a traditional field-inventory and community science project, we inventoried urban trees in the residential neighbourhood of Notre-Dame-de-Grȃce, Montreal. We assessed various green space types in the public and private domain to quantify how tree diversity, composition and structure varies across multiple land management types at local scales. We considered patterns beyond including species composition and service-traits (traits related to managers preference and ecosystem services) with implications for the distribution of ecosystem services within the urban landscape.
Results/Conclusions
We found that green space types displayed meaningful differences in both tree diversity, structure and service-based traits. For example, the inclusion of private trees contributed an additional 52 species (30% of total species) not found in the local public tree inventory, and private land was dominated by smaller trees compared to the public domain. We found patterns of richness, size and abundance extend to differences in tree composition and service-traits at local-scales, particularly in the street right-of way and private yards. Composition varied considerably across street blocks; however, blocks were very similar in terms of mean service-based traits. Contrastingly, species composition was similar from yard to yard, however, yards differed significantly in mean service-trait values. Overall, our work emphasises that public tree inventories are unlikely to be fully representative of urban forest composition and structure, with implications for urban forest management at larger spatial scales.
